Advances in steam turbine technology have generated improvements in efficiency and power generation capability. In closed systems, however, there are often losses at the margin stage buckets as steam flow seeps past the buckets between the bucket tip and the inner wall of the turbine enclosure. Reducing the physical clearance of the buckets only works to a certain extent, because certain minimum physical tolerances to permit the buckets to rotate freely must be respected. Accordingly, there is a need to reduce the effective clearance to reduce the losses of steam flow without reducing the physical clearance.